Add Wine-based runner image for Windows builds

- runner/Dockerfile: Debian + Wine + Windows CPython 3.12 + PyInstaller + act_runner
- runner/entrypoint.sh: self-register with the windows:host label
- workflow windows job now builds via winpython under Wine

.gitea/workflows/build.yml

@@ -33,26 +33,22 @@ jobs:
           path: psp-preserve-linux-x86_64.tar.gz
 
   windows:
-    name: Windows x64
+    name: Windows x64 (Wine)
     runs-on: windows
     steps:
       - uses: actions/checkout@v4
 
-      - uses: actions/setup-python@v5
-        with:
-          python-version: "3.12"
-
       - name: Install build dependencies
         run: |
-          python -m pip install --upgrade pip
-          pip install -r requirements-build.txt
+          winpython -m pip install --upgrade pip
+          winpython -m pip install -r requirements-build.txt
 
       - name: Build
-        run: pyinstaller --clean --noconfirm psp-preserve.spec
+        run: winpython -m PyInstaller --clean --noconfirm psp-preserve.spec
 
       - name: Package zip
-        shell: pwsh
-        run: Compress-Archive -Path dist\psp-preserve -DestinationPath psp-preserve-windows-x64.zip
+        run: |
+          cd dist && zip -rq ../psp-preserve-windows-x64.zip psp-preserve
 
       - uses: actions/upload-artifact@v4
         with: